Michael Poland

Time series of vertical displacements during April–October 2017 at four GPS stations (LAK1, LAK2, LKWY, and SEDG) on the north side of Yellowstone Lake. Downward trends indicate subsidence and upward trends show uplift. Uplift “spikes” in late September are related to inclement weather and do not show true deformation. Error bars are one standard deviation.

Horizontal displacements from campaign (black vectors) and continuous (red vectors, with station names given) GPS stations, as well as vertical displacements (indicated by color of GPS station symbol) near South Sister, Oregon. Length of arrow gives amount of horizontal displacement, with scale in lower left showing an arrow length

InSAR image Kīlauea, Hawai‘i, Mar. 2011. Kamoamoa fissure trace is indicated by the red line.

Map of Kīlauea Volcano showing the south-southeast motion, as recorded by continuous GPS sites (arrows), and earthquake epicenter between February 1-3, 2010.

Lava from the Pu'u 'Ō'ō-Kupaianaha eruption, active since 1983, enters the ocean on the south flank of Kīlauea Volcano.

Yellow-bellied Marmot stands on its hind legs in Yellowstone National Park. Photo by D. Dzurisin.

The USGS Hawaiian Volcano Observatory (foreground) is located on the caldera rim of Kilauea Volcano, Hawai'i—the most active volcano in the world.  The observatory's location provides an excellent view of summit eruptive activity, which began in 2008.

The USGS Hawaiian Volcano Observatory (foreground) is located on the caldera rim of Kilauea Volcano, Hawai'i—the most active volcano in the world.  The observatory's location provides an excellent view of summit eruptive activity, which began in 2008.

When lava from the Pu'u 'Ō'ō-Kupaianaha eruption, active since 1983, meets the ocean, large littoral explosions can result.

South side of Mount St. Helens lava dome, glacier (cracked snowy surface in foreground at base of dome) is being uplifted due to increase in activity. October 2, 2004.

Criteria for estimation of the Volcanic Explosivity Index (VEI).  Modified from: Newhall, C.G., and Self, S., 1982, The volcanic explosivity index (VEI): An estimate of explosive magnitude for historical volcanism. Journal of Geophysical Research, v. 87, no. C2, p.

Benchmark T366, was installed in 1987 a few miles north of Canyon Junction in Yellowstone National Park. Rather than being a brass or aluminum disk, the benchmark is a rod that was driven into the ground until it would not sink any lower.  The precise elevation of the top of the rod was established by surveying methods, and an access cover flush with the g

Geological map of Yellowstone National Park based on work by William Henry Holmes in 1878 as part of Ferdinand Vandeveer Hayden’s United States Geological and Geographical Survey of the Territories, with topography mapped by Henry Gannett and triangulation by Allen David Wilson.  From the Twelfth Annual Re